Last weekend I did a talk on How to start hacking on Valgrind by example at Fosdem which contain some Easy hacks for valgrind. If If you always wanted to hack on Valgrind, but haven’t yet really looked at the code yet, then this might be a nice introduction. Make sure to also read the slides for all the other Valgrind devroom talks. Much thanks to the Fosdem organization for letting the Valgrind hackers meet. It was a great weekend.
The case is remanded, so a new jury will first sit down and consider the fair use question. If that jury finds fair use and thus no infringement, Oracle’s next appeal will be quite weak, and the Appeals Court likely won’t reexamine the question in any detail. In that outcome, very little has changed overall: we’ll have certainty that API’s aren’t copyrightable, as long as any textual copying that occurs during reimplementation is easily called fair use. By contrast, if the new jury rejects Google’s fair use defense, I suspect Google will have to appeal all the way to SCOTUS. It’s thus going to be at least two years before anything definitive is decided, and the big winners will be wealthy litigation attorneys — as usual.
You will want to read the whole thing to know why from a copyleft perspective this decision will give that strange feeling of simultaneous annoyance and contentment.
There seems to be a nasty bug out there in some implementations of Java 7, including IcedTea7 and OpenJDK7. The bug is very public and being actively abused to circumvent security restrictions. Please upgrade to IcedTea 2.3.1 or build your packages using the patch as discussed on the OpenJDK mailinglists.
Note that if you are using the icedtea-web applet viewer then you are not directly vulnerable to the exploits as currently out there in the wild since those try to disable the SecurityManager completely and icedtea-web doesn’t allow that (some proprietary applet plugins do allow that though). But there are other ways to abuse this bug to circumvent security restrictions in a more subtle way, so patching is still very recommended.
Some classpath/icedtea servers changed networks/ip addresses on Sunday. Changes should propagate through DNS on Monday. This can cause connection errors to planet.classpath.org, builder.classpath.org (buildbot and jenkins) and icedtea.wildebeest.org (hg backups). Apologies for the late notice.
anyone is free under the Copyright Act to write his or her own code to carry out exactly the same function or specification of any methods used in the Java API
More on Groklaw.
commit 654443e20dfc0617231f28a07c96a979ee1a0239 Merge: 2c01e7b 9cba26e Author: Linus Torvalds Date: Thu May 24 11:39:34 2012 -0700 Merge branch 'perf-uprobes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull user-space probe instrumentation from Ingo Molnar: "The uprobes code originates from SystemTap and has been used for years in Fedora and RHEL kernels. This version is much rewritten, reviews from PeterZ, Oleg and myself shaped the end result. This tree includes uprobes support in 'perf probe' - but SystemTap (and other tools) can take advantage of user probe points as well. Sample usage of uprobes via perf, for example to profile malloc() calls without modifying user-space binaries. First boot a new kernel with CONFIG_UPROBE_EVENT=y enabled. If you don't know which function you want to probe you can pick one from 'perf top' or can get a list all functions that can be probed within libc (binaries can be specified as well): $ perf probe -F -x /lib/libc.so.6 To probe libc's malloc(): $ perf probe -x /lib64/libc.so.6 malloc Added new event: probe_libc:malloc (on 0x7eac0) You can now use it in all perf tools, such as: perf record -e probe_libc:malloc -aR sleep 1 Make use of it to create a call graph (as the flat profile is going to look very boring): $ perf record -e probe_libc:malloc -gR make [ perf record: Woken up 173 times to write data ] [ perf record: Captured and wrote 44.190 MB perf.data (~1930712 $ perf report | less 32.03% git libc-2.15.so [.] malloc | --- malloc 29.49% cc1 libc-2.15.so [.] malloc | --- malloc | |--0.95%-- 0x208eb1000000000 | |--0.63%-- htab_traverse_noresize 11.04% as libc-2.15.so [.] malloc | --- malloc | 7.15% ld libc-2.15.so [.] malloc | --- malloc | 5.07% sh libc-2.15.so [.] malloc | --- malloc | 4.99% python-config libc-2.15.so [.] malloc | --- malloc | 4.54% make libc-2.15.so [.] malloc | --- malloc | |--7.34%-- glob | | | |--93.18%-- 0x41588f | | | --6.82%-- glob | 0x41588f ... Or: $ perf report -g flat | less # Overhead Command Shared Object Symbol # ........ ............. ............. .......... # 32.03% git libc-2.15.so [.] malloc 27.19% malloc 29.49% cc1 libc-2.15.so [.] malloc 24.77% malloc 11.04% as libc-2.15.so [.] malloc 11.02% malloc 7.15% ld libc-2.15.so [.] malloc 6.57% malloc ... The core uprobes design is fairly straightforward: uprobes probe points register themselves at (inode:offset) addresses of libraries/binaries, after which all existing (or new) vmas that map that address will have a software breakpoint injected at that address. vmas are COW-ed to preserve original content. The probe points are kept in an rbtree. If user-space executes the probed inode:offset instruction address then an event is generated which can be recovered from the regular perf event channels and mmap-ed ring-buffer. Multiple probes at the same address are supported, they create a dynamic callback list of event consumers. The basic model is further complicated by the XOL speedup: the original instruction that is probed is copied (in an architecture specific fashion) and executed out of line when the probe triggers. The XOL area is a single vma per process, with a fixed number of entries (which limits probe execution parallelism). The API: uprobes are installed/removed via /sys/kernel/debug/tracing/uprobe_events, the API is integrated to align with the kprobes interface as much as possible, but is separate to it. Injecting a probe point is privileged operation, which can be relaxed by setting perf_paranoid to -1. You can use multiple probes as well and mix them with kprobes and regular PMU events or tracepoints, when instrumenting a task." Fix up trivial conflicts in mm/memory.c due to previous cleanup of unmap_single_vma(). * 'perf-uprobes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits) perf probe: Detect probe target when m/x options are absent perf probe: Provide perf interface for uprobes tracing: Fix kconfig warning due to a typo tracing: Provide trace events interface for uprobes tracing: Extract out common code for kprobes/uprobes trace events tracing: Modify is_delete, is_return from int to bool uprobes/core: Decrement uprobe count before the pages are unmapped uprobes/core: Make background page replacement logic account for rss_stat counters uprobes/core: Optimize probe hits with the help of a counter uprobes/core: Allocate XOL slots for uprobes use uprobes/core: Handle breakpoint and singlestep exceptions uprobes/core: Rename bkpt to swbp uprobes/core: Make order of function parameters consistent across functions uprobes/core: Make macro names consistent uprobes: Update copyright notices uprobes/core: Move insn to arch specific structure uprobes/core: Remove uprobe_opcode_sz uprobes/core: Make instruction tables volatile uprobes: Move to kernel/events/ uprobes/core: Clean up, refactor and improve the code ...
Were it grounded in reality, Oracle’s claim that copyright law gives them proprietary control over any software that uses a particular functional API would be terrible for free software and programmers everywhere. It is an unethical and greedy interpretation created with the express purpose of subjugating as many computer users as possible, and is particularly bad in this context because it comes at a time when the sun has barely set on the free software community’s celebration of Java as a language newly suitable for use in the free world. Fortunately, the claim is not yet reality, and we hope Judge Alsup will keep it that way.
Funny to see Tap the Waterdroplet (the GNU Classpath mascot) used in court to explain what Java is:
Tap makes a couple more cameo appearances in the documents. It is a fun read.
When a project keeps a GNU style ChangeLog file to keep track of who changed what where then those files can be automagically merged if you use mercurial or git.
To install it:
git clone git://git.savannah.gnu.org/gnulib.git cd gnulib ./gnulib-tool --create-testdir --dir=/tmp/testdir123 git-merge-changelog cd /tmp/testdir123 ./configure make make install
For Mercurial add the following lines to your ~/.hgrc:
[merge-patterns] ChangeLog = git-merge-changelog [merge-tools] git-merge-changelog.executable = /usr/local/bin/git-merge-changelog git-merge-changelog.args = $base $local $other
That installs the git-merge-changelog driver globally for all hg repos.
For git add the following lines to your ~/.gitconfig
[merge "merge-changelog"] name = GNU-style ChangeLog merge driver driver = /usr/local/bin/git-merge-changelog %O %A %B [core] attributesfile = ~/.gitattributes
And add the following line to ~/.gitattributes
Note: The global core.attributesfile exists only since git 1.7.4, before that you would have to configure this for each git repo separately, by doing:
cd ~/src/[repo-name] echo "ChangeLog merge=merge-changelog" >> .git/info/attributes
And never worry again about having to manually merge ChangeLog files.
The Open Invention Network patent agreement now also covers IcedTea and OpenJDK (see the new System Environment Components list). The covered version of GCC/GNU Classpath/libgcj have been updated to the latest release and various GNU Classpath[X] components have been added. As have the Eclipse SDK and ECJ. This is good news since that means the various companies which are part of OIN (Red Hat, IBM, Oracle, Google, Sony, Philips, Novell etc.) have agreed to patent cross-license and release from claims of patent infringement each other and everybody who joins OIN and agrees to collaborate in the same way around GNU/Linux and the various implementations of the java programming language.